Portion of a toothbrush



FIG. 1 is a left, frontal perspective view of a portion of toothbrush showing my new design;

FIG. 2 is a right, rear perspective view thereof:

FIG. 3 is a front view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a right side view thereof. the left side view being a mirror image thereto;

FIG. 6 is a bottom view thereof; and,

FIG. 7 is a top view thereof.

The broken lines showing a bristled head and features on the handle illustrate environmental structure and portions of the handle that form no part of the claimed design. 

The ornamental design for a portion of a toothbrush, as shown and described. 